Small scale Internal Combustion Engines (ICE) powered Combined Heat and Power (CHP) plants are economically convenient when availability and efficiencies are above specified limits. Nevertheless these plants are often run without a monitoring device capable of data storing and trending and of performance evaluation. This paper describes the setting up of a powerful low-cost monitoring system for the CHP plant that powers the School of Engineering of the University of Perugia. Data acquisition is performed by interfacing a Personal Computer (PC) to existing control panels via, serial port, and to a data acquisition board for those variables that are not measured by existing devices. Performance indexes are then calculated via software. Alarms and controls are stored as well to set up a database for diagnostic purposes. The monitoring itself has already shown its troubleshooting capability in interface to maintenance personnel: history trending of variables speeds up the phase of failure identification because it eliminates those possibilities that are negated by cross referencing values of different variables.